This invention relates to a vocal canceler for providing karaoke output from an audio or video device such as a radio or television set or video cassette recorder.
Karaoke refers to output of the musical accompaniment to a song without the singer's voice, so that the user can substitute his or her own voice. This form of entertainment has become extremely popular in Japan, where the term originated, and elsewhere. Both audio and video karaoke recordings are available. A recent idea is to equip a television set or video cassette recorder with a vocal canceler, permitting the user to create karaoke material by suppressing the singer's voice in vocal music broadcasts.
A conventional vocal canceler operates on broadcasts with stereo sound, by taking the sum and difference of the left- and right-channel sound signals. The sum signal is filtered to eliminate voice frequencies, then combined with the difference signal and supplied to both the right and left output channels. A problem with this conventional circuit is that since the left and right channels receive identical output signals, the output is monophonic, lacks spatial spread, and fails to provide the feeling of presence afforded by the original stereo signal.